PHP の session_encode() 関数と session_decode() 関数

//boolean session_encode()
session_register ( 'bgcolor' );
session_register ( 'fontcolor' );

$id = session_id ( $usr_id );

$bgcolor = "white";
$fontcolor = "blue";

$usr_data = session_encode ();

print $usr_data;
?>

session_start();
$_SESSION = array();
session_decode( "products|a:2:{i:0;s:8:"Hal 2000";i:1;s:6:"Tardis";}" );
foreach ( $_SESSION['products'] as $p ) {
 print "$pn";
}
?>